Share on Pinterest
Healthcare workers across the nation are getting the COVID-19 vaccine. Pool/Getty Images
  • To date, safety data on the vaccine has been collected from 37,586 participants enrolled in an ongoing phase 3 clinical trial.
  • The most commonly reported side effect from the vaccine is injection site reaction.
  • Other commonly reported side effects of the Pfizer-BioNTech COVID-19 vaccine include fatigue, headache, and muscle pain.

All data and statistics are based on publicly available data at the time of publication. Some information may be out of date. Visit our coronavirus hub and follow our live updates page for the most recent information on the COVID-19 pandemic.

Earlier this month, the Food and Drug Administration issued its first emergency use authorization (EUA) for a vaccine against COVID-19 in people aged 16 years and older.

Under this EUA, Pfizer-BioNTech’s new COVID-19 vaccine can now be distributed in the United States.

The FDA issued this authorization after reviewing the available efficacy and safety data on the new vaccine. Based on evidence from ongoing clinical trials, the FDA found that the known and potential benefits of the vaccine outweigh the known and potential risks.

The available data suggests that after two doses, the vaccine is 95 percent effective at preventing COVID-19. So far, research has also found that the vaccine has a good safety profile.

“Based on the large number of folks that have been closely monitored during the study, the patient safety profile is excellent in terms of side effects,” Dr. Matthew Heinz, a hospitalist based in Tucson, Arizona, told Healthline.

“Of course, we have to continue to monitor going forward. We need to continue to collect data to make sure it stays that way,” he said.

The Pfizer-BioNTech COVID-19 vaccine is administered in two doses, 3 weeks apart.

To date, safety data on the vaccine has been collected from 37,586 participants enrolled in an ongoing phase 3 clinical trial.

Among those participants, 18,801 have received the vaccine and 18,785 have received a placebo. They have been followed for a median of 2 months following vaccination.

The most commonly reported side effect from the vaccine is injection site reaction. Such reactions can cause some pain and other symptoms around the area where the vaccine is injected.

“You sometimes get some redness, some warmth, a little bit of mild swelling or firmness around the site of the injection. That’s very typical,” Heinz told Healthline.

“It can be a little tender, it can hurt to move the arm a little bit,” he continued.

Injection site reactions were reported by 84 percent of participants who received the vaccine.

In rare cases, people have developed delayed skin reactions after getting vaccinated.

In early March, a group of doctors wrote a letter to The New England Journal of Medicine describing delayed skin reactions in 12 patients who received the Moderna vaccine. This type of delay reaction might also develop in people who get the Pfizer-BioNTech vaccine.

According to the authors of the NEJM letter, the patients developed rashes, large raised red patches, or other skin symptoms around the injection site four to 11 days after getting their first dose of the vaccine.

The researchers found evidence that these symptoms were caused by a delayed allergic reaction.

The reactions were limited to the area around the injection site and not serious. Symptoms cleared within 2 to 11 days.

All 12 patients were encouraged to get a second dose of the vaccine by their doctors.

Other commonly reported side effects of the Pfizer-BioNTech COVID-19 vaccine include fatigue, headache, and muscle pain.

Fatigue has been reported by roughly 63 percent of research subjects who received the vaccine, while headache and muscle pain have affected about 55 and 38 percent of participants, respectively. In most cases, those symptoms have been mild and resolved within a day or so.

Smaller numbers of participants reported chills, joint pain, or fever following vaccination.

Participants were more likely to report such symptoms following the second dose of the vaccine.

“[The reaction to the second dose] tends to be a little more of an intense response, which does make sense, considering your immune system has been exposed already,” Heinz said.

“It gets hit with another dose of [the vaccine], and it has a sort of quicker and more robust response. That makes a lot of sense immunologically,” he added.

Among participants who received the vaccine and those who got the placebo alike, the reported rate of serious adverse events is less than 0.5 percent, with no significant differences between the two groups.

Four cases of Bell’s palsy have been reported in participants who received the vaccine, while none has been reported in those who got the placebo.

However, those four cases are consistent with the rate of Bell’s palsy in the general population. In other words, there’s no clear evidence that the Bell’s palsy was caused by the vaccine.

Severe allergic reactions to vaccines are very rare, but they can happen. The FDA recommends that people who have experienced a severe allergic reaction to a previous dose of the Pfizer-BioNTech COVID-19 vaccine, or to any of its ingredients, should not receive it.

Heinz suggested that people might want to schedule their vaccinations at a time when it’s easier to manage potential side effects such as fatigue or headache.

“Don’t do it at 9 a.m. on your way to work. Do it at the end of the day, if you work normal daytime hours, or a day when you’re already going to be off — that kind of thing,” he said.

If you develop pain around the injection site, it may be treated with over-the-counter medication. Such medications may also help relieve fever, headache, muscle pain, or joint pain.

“A couple of Advil and a dose of Tylenol to help with discomfort and swelling — that’s all it should really require,” Heinz said.

If you develop side effects that are bothersome or do not resolve, contact your healthcare provider. If you think you might be having a severe allergic reaction, call 911 or go to the emergency room.

It’s important to recognize that some side effects from the Pfizer-BioNTech COVID-19 vaccine are common and normal. If you experience mild to moderate side effects after the first dose, that doesn’t mean you should skip the second dose.

“Your immunity is incomplete [after one dose], and it might not be effective. So you have more than likely wasted the first dose, if you don’t get the second one in time,” Dr. Waleed Javaid, an associate professor of infectious disease at Icahn School of Medicine at Mount Sinai in New York City, he said.

If you have questions or concerns about the vaccine, Javaid recommends speaking with your healthcare provider.

He noted that it’s important to consider the potential benefits of the vaccine, as well as the potential risks.

“Why are we getting the COVID vaccine to begin with? Because we are in a big pandemic. We know the real consequence of not having immunity to COVID, which can lead to somebody’s death,” Javaid told Healthline.

“Injection site reactions, some aches and pains, some other potential side effects — versus death. That’s the balance people have to think about,” he said.